U.S. patent application number 13/530738 was filed with the patent office on 2013-12-26 for method for producing purified dialkyl-furan-2,5-dicarboxylate vapor.
This patent application is currently assigned to EASTMAN CHEMICAL COMPANY. The applicant listed for this patent is Mesfin Ejerssa Janka, Kenny Randolph Parker, Lee Reynolds Partin, Ashfaq Shaikh. Invention is credited to Mesfin Ejerssa Janka, Kenny Randolph Parker, Lee Reynolds Partin, Ashfaq Shaikh.
Application Number | 20130345447 13/530738 |
Document ID | / |
Family ID | 48652365 |
Filed Date | 2013-12-26 |
United States Patent
Application |
20130345447 |
Kind Code |
A1 |
Shaikh; Ashfaq ; et
al. |
December 26, 2013 |
METHOD FOR PRODUCING PURIFIED DIALKYL-FURAN-2,5-DICARBOXYLATE
VAPOR
Abstract
Disclosed is a process to produce a purified vapor comprising
dialkyl-furan-2,5-dicarboxylate (DAFD). Furan-2,5-dicarboxylic acid
(FDCA) and an alcohol in an esterification zone to generate a crude
diester stream containing dialkyl furan dicarboxylate (DAFD),
unreacted alcohol, 5-(alkoxycarbonyl)furan-2-carboxylic acid
(ACFC), and alkyl furan-2-carboxylate (AFC). The crude diester
stream is fed to a flash evaporation zone to produce a vapor
alcohol composition and a first liquid DAFD rich composition. At
least a portion of the remaining alcohol can be separated from the
first liquid DAFD rich composition to produce a second alcohol
vapor and a second liquid DAFD rich composition, followed by
separating AFC from the second liquid DAFD rich composition to
product an AFC vapor and a partially purified DAFD rich
composition, followed by separating a portion of the DAFD from the
partially purified DAFD rich composition to produce a purified DAFD
vapor.
Inventors: |
Shaikh; Ashfaq; (Kingsport,
TN) ; Partin; Lee Reynolds; (Kingsport, TN) ;
Janka; Mesfin Ejerssa; (Kingsport, TN) ; Parker;
Kenny Randolph; (Afton, TN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Shaikh; Ashfaq
Partin; Lee Reynolds
Janka; Mesfin Ejerssa
Parker; Kenny Randolph |
Kingsport
Kingsport
Kingsport
Afton |
TN
TN
TN
TN |
US
US
US
US |
|
|
Assignee: |
EASTMAN CHEMICAL COMPANY
Kingsport
TN
|
Family ID: |
48652365 |
Appl. No.: |
13/530738 |
Filed: |
June 22, 2012 |
Current U.S.
Class: |
549/485 |
Current CPC
Class: |
C07D 307/68
20130101 |
Class at
Publication: |
549/485 |
International
Class: |
C07D 307/68 20060101
C07D307/68 |
Claims
1. A process for the manufacture of a DAFD vapor comprising: a.
feeding a furan-2,5-dicarboxylic acid ("FDCA") composition to an
esterification reaction zone; and b. in the presence of an alcohol
compound, conducting an esterification reaction in the
esterification reaction zone to react FDCA with said alcohol
compound to form a crude diester composition comprising dial kyl
furan-2,5-dicarboxylate ("DAFD"), the alcohol compound,
5-(alkoxycarbonyl)furan-2-carboxylic acid (ACFC), alkyl
furan-2-carboxylate (AFC), and alkyl-5-formylfuran-2-carboxylate
(AFFC), and c. separating at least a portion of the alcohol
compound from the crude diester composition in a flash zone using a
physical separation process to produce: (i) a vapor alcohol
composition, comprising said alcohol compound, taken as an overhead
stream that is rich in the concentration of alcohol, relative to
the alcohol concentration in the crude diester composition feeding
the flash zone, and (ii) a first liquid DAFD rich composition,
comprising DAFD, ACFC, AFC, and AFFC, that is rich in the total
concentration of DAFD relative to the total concentration of DAFD
in the crude diester composition feeding the flash zone; and d.
separating at least a portion of DAFD from the first liquid DAFD
rich composition in a product recovery zone; wherein the process
produces: (i) a purified DAFD vapor composition rich in the
concentration of DAFD relative to the concentration of DAFD in the
first liquid DAFD rich composition; and (ii) a liquid ACFC
composition that is rich in the concentration of ACFC relative to
the concentration of ACFC in the first liquid DAFD rich
composition; and (iii) a vapor AFC composition comprising AFC that
is rich in the concentration of AFC relative to the concentration
of AFC in the first liquid DAFD rich composition; and (iv) a second
alcohol composition comprising alcohol that is rich in the
concentration of alcohol, relative to the first liquid DAFD rich
composition.
2. The process of claim 1, wherein the alcohol comprises methanol,
the DAFD comprises dimethyl-furan-2,5-dicarboxylate ("DMFD"), the
ACFC comprises 5-(methoxycarbonyl)furan-2-carboxylic acid (MCFC),
the AFC comprises methyl furan-2-carboxylate (MFC), and the AFFC
comprises methyl 5-formylfuran-2-carboxylate (MFFC).
3. The process of claim 1, wherein the physical separation in step
c comprises a flash tank.
4. The process of claim 3, wherein the physical separation in step
d comprises at least two distillation columns.
5. The process of claim 1, wherein the first liquid DAFD rich
composition comprises from 30 wt. % to 80 wt. % DAFD and alcohol
present in an amount of no more than 60 wt. %, each based on the
weight of the first liquid DAFD rich composition.
6. The process of claim 1, wherein the concentration of DAFD in the
first liquid DAFD rich composition is increased by at least 250%
over the concentration of DAFD in the crude diester
composition.
7. The process of claim 1, wherein the vapor AFC composition
comprises at least 15 wt. % AFC, and less than 3 wt. % DAFD, each
based on the weight of the vapor AFC composition.
8. The process of claim 1, wherein the vapor AFC composition
comprises AFC and AFFC in a cumulative amount of at least 90 wt. %
based on the weight of the vapor AFC composition.
9. The process of claim 1, wherein the concentration of AFC in the
vapor AFC composition is increased by a factor of at least
15.times. relative to the concentration of AFC in the second liquid
DAFD rich composition.
10. The process of claim 1, wherein the purified DAFD vapor
composition comprises DAFD in an amount of greater than 99.0 wt. %
and less than 1000 ppm ACFC, each based on the weight of purified
DAFD vapor composition.
11. The process of claim 1, wherein the liquid ACFC composition
comprises ACFC in an amount of at least 30 wt. % and DAFD in an
amount of less than 50 wt. %.
12. The process of any one of claims 1-11, wherein step d comprises
separating at least a portion of alcohol from the first liquid DAFD
rich composition using a physical separation process to produce: d
(i) a second alcohol composition that is rich in the concentration
of alcohol relative to the concentration of alcohol in the first
liquid DAFD rich composition; and d(ii) a second liquid DAFD rich
composition comprising DAFD that is rich in the concentration of
DAFD relative to the concentration of DAFD in the first liquid DAFD
rich composition; and wherein said process further comprises: e .
separating at least a portion of AFC from the second liquid DAFD
rich composition using a physical separation process to produce:
e(i) a vapor AFC composition that is rich in the concentration of
AFC relative to the concentration of AFC in the second liquid DAFD
rich composition; and e(ii) a partially purified liquid DAFD rich
composition comprising DAFD and ACFC that is rich in the
concentration of DAFD relative to the concentration of DAFD in the
second liquid DAFD rich composition; and f. separating at least a
portion of the DAFD from the partially purified DAFD rich
composition using a physical separation process to produce: f(i) a
purified DAFD vapor composition rich in the concentration of DAFD
relative to the concentration of DAFD in the partially purified
liquid DAFD rich composition; and f(ii) a liquid ACFC composition
that is rich in the concentration of ACFC relative to the
concentration of ACFC in the partially purified liquid DAFD rich
composition.
13. The process of claim 12, wherein the concentration of DAFD in
the second liquid DAFD rich composition is at least 85 wt. %, and
the concentration of alcohol is less than 0.1 wt. %, each based on
the weight of the second liquid DAFD rich composition and the
concentration of alcohol .
14. The process of claim 12, wherein the concentration of DAFD in
the second liquid DAFD rich composition is higher than the
concentration of DAFD in the first liquid DAFD rich composition by
at least 30 wt %.
15. The process of claim 12, wherein the concentration of DAFD in
the partially purified liquid DAFD rich composition is at least 95
wt. % and up to 99.9 wt. %, and the amount of ACFC is at least 1.0
wt. %, each based on the weight of the partially purified liquid
DAFD rich composition.
16. The process of claim 12, wherein the concentration of AFC in
the partially purified liquid DAFD rich composition is depleted
relative to the concentration of DAFD in the second liquid DAFD
rich composition by a factor of at least 750.times..
17. The process of claim 12, wherein the vapor AFC composition
further comprises AFFC, and the concentration of AFC in the vapor
AFC composition is at least 15 wt. %, and the concentration of AFFC
in the vapor AFC composition is at least 40 wt. %, each based on
the weight of the vapor AFC composition.
18. The process of claim 12, wherein the concentration of AFC in
the vapor AFC composition is higher than the concentration of AFC
in the second liquid DAFD rich composition be a factor of at least
15.times..
19. The process of claim 12, wherein the concentration of ACFC in
the liquid ACFC composition is at least 30 wt. % and the amount of
DAFD is less than 50 wt. %, each based on the weight of the liquid
ACFC composition.
20. The process of claim 12, wherein the concentration of ACFC in
the liquid ACFC composition is higher than the concentration of
ACFC in the partially purified liquid DAFD rich composition by a
factor of at least 10.times..
21. The process of claim 12, wherein the concentration of ACFC in
the DAFD vapor composition is depleted relative to the
concentration of ACFC in the partially purified liquid DAFD rich
composition by a factor of at least 200.times..
22-30. (canceled)
Description
1. FIELD OF THE INVENTION
[0001] The invention relates to the processes for the production of
purified dialkyl-furan-2,5-dicarboxylate (DAFD) vapor and purified
DAFD compositions made therefrom.
2. BACKGROUND OF THE INVENTION
[0002] Aromatic dicarboxylic acids such as terephthalic acid and
isophthalic acid or their di-esters, dimethyl terephthalate as for
example, are used to produce a variety of polyester products,
important examples of which are poly (ethylene terephthalate) and
its copolymers. The aromatic dicarboxylic acids are synthesized by
the catalytic oxidation of the corresponding dialkyl aromatic
compounds which are obtained from fossil fuels such as those
disclosed in US 2006/0205977 A1. Esterification of these diacids
using excess alcohol produces the corresponding di-esters has been
disclosed in US2010/0210867A1. There is a growing interest in the
use of renewable resources as feed stocks for the chemical
industries mainly due to the progressive reduction of fossil
reserves and their related environmental impacts.
[0003] Furan-2,5-dicarboxylic acid ("FDCA") is a versatile
intermediate considered as a promising closest biobased alternative
to terephthalic acid and isophthalic acid. Like aromatic diacids,
FDCA can be condensed with diols such as ethylene glycol to make
polyester resins similar to polyethylene terephthalate (PET) as
disclosed in Gandini, A.; Silvestre, A. J; Neto, C. P.; Sousa, A.
F.; Gomes, M. J. Poly. Sci. A 2009, 47, 295. FDCA has been prepared
by oxidation of 5-(hydroxymethyl) furfural (5-HMF) under air using
homogenous catalysts as disclosed in US2003/0055271 A1 and in
Partenheimer, W.; Grushin, V. V. Adv. Synth. Catal. 2001, 343,
102-111. However, achieving high yields has proved difficult. A
maximum of 44.8% yield using Co/Mn/Br catalysts system and a
maximum of 60.9% yield was reported using Co/Mn/Br/Zr catalysts
combination.
[0004] The crude FDCA obtained by the oxidation processes must to
be purified before they are suitable for end-use applications. JP
patent application, JP209-242312A, disclosed crude FDCA
purification process using sodium hydroxide/sodium hypochlorite
and/or hydrogen peroxide followed by acid treatment of the disodium
salt to obtain pure FDCA. This multi-step purification process
generates wasteful by-products.
[0005] Therefore, there is a need for an inexpensive and high yield
process for the purification of crude FDCA that minimizes the
creation of additional waste products and lends itself to efficient
separation step(s).
3. SUMMARY OF THE INVENTION
[0006] There is now provided a process for the manufacture of DAFD
vapor comprising: [0007] a. feeding a furan-2,5-dicarboxylic acid
("FDCA") composition to an esterification reaction zone; and [0008]
b. in the presence of an alcohol compound, conducting an
esterification reaction in the esterification reaction zone to
react FDCA with said alcohol compound to form a crude diester
composition comprising dialkyl furan-2,5-dicarboxylate ("DAFD"),
the alcohol compound, 5-(alkoxycarbonyl)furan-2-carboxylic acid
(ACFC), alkyl furan-2-carboxylate (AFC), and
alkyl-5-formylfuran-2-carboxylate (AFFC), and [0009] c. separating
at least a portion of the alcohol compound from the crude diester
composition in a flash zone using a physical separation process to
produce: [0010] (i) a vapor alcohol composition, comprising said
alcohol compound, taken as an overhead stream that is rich in the
concentration of alcohol, relative to the alcohol concentration in
the crude diester composition feeding the flash zone, and [0011]
(ii) a first liquid DAFD rich composition, comprising DAFD, ACFC,
AFC, and AFFC, that is rich in the total concentration of DAFD
relative to the total concentration of DAFD in the crude diester
composition feeding the flash zone; and [0012] d. separating at
least a portion of DAFD from the first liquid DAFD rich composition
in a product recovery zone; [0013] wherein the process produces:
[0014] (i) a purified DAFD vapor composition rich in the
concentration of DAFD relative to the concentration of DAFD in the
first liquid DAFD rich composition; and [0015] (ii) a liquid ACFC
composition that is rich in the concentration of ACFC relative to
the concentration of ACFC in the first liquid DAFD rich
composition; and [0016] (iii) a vapor AFC composition comprising
AFC that is rich in the concentration of AFC relative to the
concentration of AFC in the first liquid DAFD rich composition; and
[0017] (iv) a second alcohol composition comprising alcohol that is
rich in the concentration of alcohol, relative to the first liquid
DAFD rich composition. [0018] Step d further comprises separating
at least a portion of alcohol from the first liquid DAFD rich
composition using a physical separation process to produce: [0019]
d(i) a second alcohol composition that is rich in the concentration
of alcohol relative to the concentration of alcohol in the first
liquid DAFD rich composition; and [0020] d(ii) a second liquid DAFD
rich composition comprising DAFD that is rich in the concentration
of DAFD relative to the concentration of DAFD in the first liquid
DAFD rich composition; and [0021] wherein said process further
comprises: [0022] e. separating at least a portion of AFC from the
second liquid DAFD rich composition using a physical separation
process to produce: [0023] e(i) a vapor AFC composition that is
rich in the concentration of AFC relative to the concentration of
AFC in the second liquid DAFD rich composition; and [0024] e(ii) a
partially purified liquid DAFD rich composition comprising DAFD and
ACFC that is rich in the concentration of DAFD relative to the
concentration of DAFD in the second liquid DAFD rich composition;
and [0025] f. separating at least a portion of the DAFD from the
partially purified DAFD rich composition using a physical
separation process to produce: [0026] f(i) a purified DAFD vapor
composition rich in the concentration of DAFD relative to the
concentration of DAFD in the partially purified liquid DAFD rich
composition; and [0027] f(ii) a liquid ACFC composition that is
rich in the concentration of ACFC relative to the concentration of
ACFC in the partially purified liquid DAFD rich composition. [0028]
There is also provided a process for the preparation of the FDCA
that is fed to the esterification reaction zone. [0029] There is
also provided a purified dialkyl furan dicarboxylate (DAFD) vapor
composition comprising: [0030] (i) at least 99.5 wt. % DAFD; [0031]
(ii) 5-(alkoxycarbonyl)furan-2-carboxylic acid (ACFC) present and
is present in an amount of not more than 1000 ppm, and [0032] (iii)
alkyl-5-formylfuran-2-carboxylate (AFFC) present and is present
[0033] in an amount of not more than 1000 ppm, [0034] in each case
based on the weight of the DAFD vapor composition. [0035] There is
also provided a purified liquid DAFD composition comprising: [0036]
(i) at least 99.9 wt. % liquid DAFD; [0037] (ii)
5-(alkoxycarbonyl)furan-2-carboxylic acid (ACFC) present and is
present in an amount of not more than 1000 ppm, and [0038] (iii)
alkyl-5-formylfuran-2-carboxylate (AFFC) present and is present in
an amount of not more than 1000 ppm, [0039] (iv) not more than 1
wt. % water, and [0040] (v) not more than 1 wt. % solids, [0041] in
each case based on the weight of the purified liquid DAFD
composition. [0042] There is also provided a solids DAFD
composition comprising solid particles of DAFD, wherein said solids
comprise: [0043] (i) at least 99.9 wt. % DAFD; [0044] (ii)
5-(alkoxycarbonyl)furan-2-carboxylic acid (ACFC) present and is
present in an amount of not more than 1000 ppm, and [0045] (iii)
alkyl-5-formylfuran-2-carboxylate (AFFC) present and is present in
an amount of not more than 1000 ppm, [0046] wherein the composition
contains not more than 1 wt. % water.
4. BRIEF DESCRIPTION OF THE DRAWINGS
[0047] FIG. 1 is a flow diagram of the process for making both FDCA
and purified DAFD.
[0048] FIG. 2 is a flow diagram illustrating a feed of raw
materials to a mixing zone prior to feeding the slurry to an
esterification reactor.
[0049] FIG. 3 is a flow diagram depicting the process of producing
a purified DAFD vapor composition using a combination of separation
zones.
5. DETAILED DESCRIPTION OF THE INVENTION
[0050] It should be understood that the following is not intended
to be an exclusive list of defined terms. Other definitions may be
provided in the foregoing description, such as, for example, when
accompanying the use of a defined term in context.
[0051] As used herein, the terms "a," "an," and "the" mean one or
more.
[0052] As used herein, the terms "comprising," "comprises," and
"comprise" are open-ended transition terms used to transition from
a subject recited before the term to one or more elements recited
after the term, where the element or elements listed after the
transition term are not necessarily the only elements that make up
the subject.
[0053] As used herein, the terms "containing," "having," "has," and
"have" have the same open-ended meaning as "comprising,"
"comprises," and "comprise" provided above.
[0054] As used herein, the terms "including," "includes," and
"include" have the same open-ended meaning as "comprising,"
"comprises," and "comprise" provided above.
[0055] The present description uses numerical ranges to quantify
certain parameters relating to the invention. It should be
understood that when numerical ranges are provided, such ranges are
to be construed as providing literal support for claim limitations
that only recite the lower value of the range as well as claim
limitations that only recite the upper value of the range. For
example, a disclosed numerical range of 10 to 100 provides literal
support for a claim reciting "greater than 10" (with no upper
bounds) and a claim reciting "less than 100" (with no lower
bounds).
[0056] The present description uses specific numerical values to
quantify certain parameters relating to the invention, where the
specific numerical values are not expressly part of a numerical
range. It should be understood that each specific numerical value
provided herein is to be construed as providing literal support for
a broad, intermediate, and narrow range. The broad range associated
with each specific numerical value is the numerical value plus and
minus 60 percent of the numerical value, rounded to two significant
digits. The intermediate range associated with each specific
numerical value is the numerical value plus and minus 30 percent of
the numerical value, rounded to two significant digits. The narrow
range associated with each specific numerical value is the
numerical value plus and minus 15 percent of the numerical value,
rounded to two significant digits. For example, if the
specification describes a specific temperature of 62.degree. F.,
such a description provides literal support for a broad numerical
range of 25.degree. F. to 99.degree. F. (62.degree. F.+/-37.degree.
F.), an intermediate numerical range of 43.degree. F. to 81.degree.
F. (62.degree. F.+/-19.degree. F.), and a narrow numerical range of
53.degree. F. to 71.degree. F. (62.degree. F.+/-9.degree. F.).
These broad, intermediate, and narrow numerical ranges should be
applied not only to the specific values, but should also be applied
to differences between these specific values. Thus, if the
specification describes a first pressure of 110 psia and a second
pressure of 48 psia (a difference of 62 psia), the broad,
intermediate, and narrow ranges for the pressure difference between
these two streams would be 25 psia to 99 psia, 43 psia to 81 psia,
and 53 psia to 71 psia, respectively.
[0057] The word "rich" in reference to a composition means the
concentration of the referenced ingredient in the composition is
higher than the concentration of the same ingredient in the feed
composition to the separation zone by weight. For example, a liquid
DAFD rich composition means that the concentration of DAFD in the
liquid DAFD rich composition is greater than the concentration of
DAFD in the stream feeding the separation zone, in this case, the
crude diester composition.
[0058] All amounts are by weight unless otherwise specified. All
references to ppm are on a mass basis.
[0059] As illustrated in FIG. 1, a dicarboxylic acid composition
stream 410, which can be either dried carboxylic acid solids or a
wet cake containing carboxylic acid, in each case the carboxylic
acid comprising furan dicarboxylic acid ("FDCA.revreaction.), and
an alcohol composition stream 520 are fed to the esterification
reaction zone 500. The solid dicarboxylic acid composition 410 can
be shipped via truck, ship, or rail as solids to a plant or
facility for the manufacture of the diester composition. The
process for the oxidation of the oxidizable material containing the
furan group can be integrated with the process for the manufacture
of the diester composition. An integrated process includes
co-locating the two manufacturing facilities, one for oxidation and
the other for esterification, within 10 miles, or within 5 miles,
or within 2 miles, or within 1 mile, or within 1/2 mile of each
other. An integrated process also includes having the two
manufacturing facilities in solid or fluid communication with each
other. If a solid dicarboxylic acid composition is produced, the
solids can be conveyed by any suitable means, such as air or belt,
to the esterification facility. If a wet cake dicarboxylic acid
composition is produced, the wet cake can be moved by belt or
pumped as a liquid slurry to the facility for esterification.
[0060] The esterification zone 500 comprises at least one
esterification reactor. The dicarboxylic acid composition
comprising FDCA is fed to the esterification zone and, in the
presence of an alcohol compound, an esterification reaction is
conducted in the esterification reaction zone to react FDCA with
said alcohol compound to form a crude diester composition
comprising dialkyl furan-2,5-dicarboxylate ("DAFD"), the alcohol
compound,5-(alkoxycarbonyl)furan-2-carboxylic acid (ACFC), alkyl
furan-2-carboxylate (AFC), and alkyl-5-formylfuran-2-carboxylate
(AFFC). The crude diester composition may optionally contain a
catalyst if a homogeneous esterification catalyst is used.
[0061] The alcohol composition comprises one or more types of
alcohol compounds. Examples include compounds represented by the
structure R--OH wherein R can range from 1 to 6 carbons, or 1 to 5
carbon atoms, or 1 to 4 carbon atoms, or 1 to 3 carbon atoms, or 1
to 2 carbon atoms, preferably methanol. R can be branched or
unbranched, saturated or unsaturated, and cyclic or acyclic.
Desirably, R is an unbranched, saturated, acyclic alkyl group. The
alcohol composition contains at least 50 wt. %, or at least 60 wt
%, or at least 70 wt %, or at least 80 wt. %, or at least 90 wt. %,
or at least 95 wt %, or at least 97 wt %, or at least 98 wt. %, or
at least 99 wt. % alcohol compounds based on the weight of the
alcohol composition. Desirably, the alcohol composition comprises
methanol.
[0062] The crude diester composition produced in the esterification
zone 500 is the reaction product of at least FDCA with the alcohol
composition to produce DAFD, where the alkyl moiety is an alkyl
group containing 1 to 6 carbon atoms, and at least a portion of the
alkyl moiety corresponds to the alcohol residue. In the case of a
reaction between FDCA and methanol, the diester reaction product
comprises dimethyl furan-2,5-dicarboxylate ("DMFD"). The
esterification reaction of FDCA with methanol to produce DMFD
comprises multiple reaction mechanisms as illustrated below. One
reaction mechanism comprises reacting one mole of FDCA with one
mole of Methanol to produce a mole of
5-(methoxycarbonyl)furan-2-carboxylic acid (MCFC) and water. One
mole of MCFC can then react with one mole of methanol to produce
one mole of the desired product DMFD and water. Because both DMFD
and MCFC are present in an esterification reaction zone, the crude
diester composition will also contain MCFC in addition to the
unreacted hydroxyl compounds and DMFD. A commercial process to
produce purified DMFD must allow for the separation of DMFD and
MCFC downstream of the esterification zone.
##STR00001##
[0063] Esterification by-products are also formed in reaction zone
500 and comprise chemicals with boiling points both higher and
lower than DMFD. Esterification by-products formed in the
esterification reaction zone comprise methyl acetate, alkyl
furan-2-carboxylate (AFC), alkyl 5-formylfuran-2-carboxylate
(AFFC), and 5-(alkoxycarbonyl)furan-2-carboxylic acid (ACFC). Many
other by-products are possible depending upon the impurities
contained within the FDCA feedstock. A commercial process to
produce a purified DAFD stream must allow for the separation of
impurities from the crude di-ester composition exiting as stream
510. Further, at least a portion of these impurities can be purged
from the process wherein purging involves isolation of the
impurities and routing them from the process.
[0064] It is desirable to first mix the FDCA composition with the
alcohol prior to conducting an esterification reaction under
esterification conditions. As illustrated in FIG. 2, there is
provided a mixing zone 540 and esterification reactor 550 within
the esterification zone 500. The dicarboxylic acid composition 410
comprising FDCA, an alcohol composition 520, optionally an
esterification catalyst system 530, and optionally an alcohol
recycle stream 802 comprising a recycled alcohol at least one of
which is the same type of compounds as fed in stream 520 are mixed
in the mixing zone 540 to generate mixed reactor feed stream 501.
In one embodiment, streams 520 and 802 comprise methanol.
[0065] Mixing in zone 540 may be accomplished by any equipment
known in the art for mixing liquid and solids, such as continuous
in line static mixers, batch agitated vessels, and or continuous
agitated vessels, and the like. The theoretical amount of alcohol
required for the reaction with each mole of FDCA in the
esterification zone, or the esterification reactor 550, or in the
mixing zone 540, is two moles. The total amount of alcohol present
in mixing zone 540 is desirably in excess of the theoretical amount
required for the esterification reaction.
[0066] For example, the molar ratio of alcohol to FDCA moles ranges
from greater than 2:1, or at least 2.2:1, or at least 2.5:1, or at
least 3:1, or at least 4:1, or at least 8:1, or at least 10:1, or
at least 15:1, or at least 20:1, or at least 25:1, or at least 30:1
and can go as high as 40:1. Suitable molar ratios are within a
range of alcohol to FDCA from 10:1 to 30:1.
[0067] To the mixing zone 540 may also be fed an esterification
catalyst system as stream 530 if a catalyst is used. The catalyst
is can be heterogeneous or desirably a homogenous catalyst under
esterification reaction conditions, and can also be homogeneous in
the mixing zone. Known organometallic esterification catalysts can
be used such as the acetate or other carboxylate or glycolate of
cobalt, copper and manganese, cadmium, lead, lithium, and zinc in
amounts conventionally used for esterifying terephathalic acid.
Other organic catalysts can be employed such as sulfuric acid,
tosylic acid, and Lewis acids.
[0068] The mixed reactor feed stream 501 is routed to
esterification reactor 550 to generate a crude diester composition
discharged from the esterification reactor 550 as liquid crude
diester stream 510. The crude diester composition 510 discharged
from the esterification zone 500 desirably contains DAFD present in
an amount of at least 5 wt %, or at least 8 wt. %, or at least 10
wt. %, or at least 15 wt. %, or at least 20 wt. %, and up to 40 wt.
%, or up to 35 wt. %, based on the weight of the whole crude
diester composition, and desirably in each case based on the weight
of the liquid phase. At the high temperatures, high pressure,
and/or high alcohol concentration under esterification conditions,
the DAFD present in the crude diester composition is solubilized
and the solids concentration is generally not more than 5 wt. %, or
not more than 2 wt. %, or not more than 1 wt. %, or not more than
0.5 wt. %, or not more than 0.1 wt. %, although the amount of
solids can be higher as the concentration of unreacted alcohol is
diminished and the reaction temperature is reduced. If solids are
present, at least 95 wt. %, or at least 96 wt. %, or at least 97
wt. %, or at least 98 wt. %, or at least 99 wt. % of the solids are
unreacted FDCA solids.
[0069] The yield of DAFD in the crude diester composition desirably
high. Suitable yields are at least 55 mole %, or at least 60 mole
%, or at least 65%, or at least 70 mole %, or at least 75 mole %,
or at least 80 mole %, or at least 85 mole %, or at least 90 mole
%, or at least 95 mole %, or at least 99 mole %. The yield of DAFD
in the crude diester stream is calculated as follows:
(mol of DAFD in the crude diester composition in the liquid
phase/starting mol of FDCA)*100%.
[0070] The crude FDCA slurry stream can be fed into the
esterification reactor at a rate corresponding to a desired
throughput in a continuous process for the production of a purified
DAFD vapor composition. Examples of suitable rates for the
production of a purified DAFD vapor composition stream include an
average of at least 1000 kg/day, or at least 10,000 kg/day, or at
least 20,000 kg/day, or at least 50,000 kg/day, or at least 75,000
kg/day, or at least 100,000 kg/day, or at least 200,000 kg/day of a
purified DAFD vapor composition, on a 24 hour basis over the course
of any three months.
[0071] Esterification may be accomplished in batch or continuous
reactors and comprises one or multiple reaction vessels that are
capable of providing acceptable reaction residence time,
temperature, and pressure. The esterification reaction residence
time ranges from 0.5 hr to about 10 hours. The esterification
temperature ranges from 150.degree. C. to below the supercritical
temperature of the alcohol selected to ensure that the alcohol
stays in liquid phase at reaction pressures. Suitable reaction
temperatures can range from 150.degree. C. to 250.degree. C., or
150.degree. C. to 240.degree. C., or from 200.degree. C. to
230.degree. C. Particularly suitable is an upper range of
240.degree. C. in the case methanol is used as the alcohol. The
esterification pressure within the esterification reactor is
sufficient to maintain the alcohol compound in the liquid phase and
will vary with the temperature selected. Suitable pressure ranges
are from about 250 psig to about 2000 psig, or from 400 psig to
1500 about psig.
[0072] The crude diester composition is taken from the
esterification reactor in the esterification zone 500 in a stream
510 and fed to a flash zone 600 as shown in FIG. 1. At least a
portion of alcohol compound in the crude diester composition is
separated from the crude diester stream in the flash zone 600 in a
physical separation process to produce a first liquid DAFD rich
composition stream 620 containing liquid DAFD, and in which the
concentration of DAFD in the DAFD rich composition is higher than
the concentration of DAFD in the crude diester composition feeding
the flash zone 600. In the flash zone, the crude diester
composition experiences a pressure letdown to flash alcohol
resulting also in evaporative cooling.
[0073] The crude diester composition exits the esterification zone
500 at elevated temperatures, typically at a temperature of at
least 150.degree. C., or at least 170.degree. C., or at least
180.degree. C., or at least 190.degree. C., or at least 200.degree.
C., or at least 210.degree. C., or at least 220.degree. C., or at
least 230.degree. C., or at least 240.degree. C., and in each case
below the supercritical temperature of the alcohol. To take
advantage of the sensible heat energy already present in crude
diester composition, one may simply conduct the physical separation
under a pressure that is lower relative to the pressure over the
crude diester stream upon entry into the separation zone, and
thereby take off alcohol through reduced pressure to produce a
first liquid DAFD rich composition as stream 620. This can be
accomplished without applying heat energy to the separation vessel
for separation purposes to thereby reduce energy consumption (e.g.
adiabatic flash).
[0074] The flash zone 600 can comprise one or more vessels for
flash separation through pressure reduction operated in series or
parallel without application of external heat energy to effect the
separation. For example, the flash zone 600 can comprise one or
more evaporative flash unit operations, or can comprise one or more
distillation columns. The alcohol separation zone can comprise both
a flash evaporation unit and a distillation column. The separation
zone may be operated in a batch or continuous mode.
[0075] Desirably, the flash zone 600 contains at least a flash
evaporation unit such as a flash tank. One may conduct staged flash
evaporation in multiple vessels. The pressure in the flash unit
operation can range from 0 psig to about 150 psig, or from 0 psig
to about 50 psig, or from 0 psig to 35 psig. If alcohol is
separated under a reduced pressure relative to the pressure of the
crude diester composition at the entry to the physical separation
vessel, it is desirable that the pressure within the flash vessel
is below the vapor pressure of the alcohol at the temperature of
the crude diester stream at the entry port to the flash vessel.
[0076] The temperature of the first liquid DAFD rich composition
stream 620 discharged from the flash zone 600 is not particularly
limited. It will be lower than the temperature of the crude diester
stream entering the flash zone due to evaporative cooling. In one
embodiment, the temperature of the first liquid DAFD rich
composition stream 620 is at least 5.degree. C. cooler, or at least
20.degree. C. cooler, or at least 50.degree. C. cooler, or at least
75.degree. C. cooler, or at least 100.degree. C. cooler, or at
least 120.degree. C. cooler than the crude diester composition
temperature entering the flash zone 600. One may employ a series of
flash vessels that have small incremental temperature drops such
that the cumulative temperature drop of all the vessels within the
zone add up to at least these stated values.
[0077] A vapor alcohol composition stream 610 is generated in the
flash zone 600. The vapor alcohol composition stream 610 comprises
alcohol, some water, and optionally a small (e.g. less than 0.1 wt
%) DAFD can also be present. The vapor alcohol composition stream
610 is rich in the concentration of alcohol, relative to the
alcohol concentration in the crude diester composition 510.
Desirably, the concentration of alcohol in the vapor alcohol
composition 610 comprises at least 70 wt. % alcohol, or at least 80
wt. % alcohol, or at least 90 wt. %, or at least 95 wt. %
alcohol.
[0078] The vapor alcohol composition stream 610 is fed to an
alcohol recovery zone 800. The alcohol recovery zone generates a
purified alcohol stream 802 comprising alcohol that is depleted in
the concentration of water alcohol relative to the concentration of
water in the vapor alcohol composition stream 610, and generates a
water stream 801 that is rich in the concentration of water
relative to the concentration of water in the vapor alcohol stream
610.
[0079] The alcohol recovery zone 800 can comprise one or more
distillation columns to effect the separation of alcohol from
water. The distillation column can be dedicated to receive a feed
of the vapor alcohol composition 610 or the vapor alcohol
composition 610 can be first condensed and fed to the distillation
column. The purified alcohol composition 802 may be one or more
vapor distillates and if desired, at least a portion can be
condensed and at least a portion can be fed as a recycle stream
back to the esterification zone 500.
[0080] Alternatively, the vapor alcohol composition gaseous
overhead stream 610, or liquid if condensed, can be fed to a shared
distillation column in alcohol recovery zone 800 that also receives
a feed of a second alcohol rich stream 712. It is desired to use a
shared distillation apparatus to reduce capital costs.
[0081] The first liquid DAFD rich composition stream 620 comprises
DAFD rich (a higher concentration) in the concentration of DAFD
relative to the concentration of DAFD present in the crude diester
stream 510 exiting the esterification zone 500. The concentration
of DAFD in the DAFD rich stream can be increased by at or at least
20%, or at least 30%, or at least 40%, or at least 50%, or at least
70%, or at least 90%, or at least 100%, or at least 150%, or at
least 200%, or at least 250%, or at least 300%, or at least 400%,
or at least 500%, over the concentration of DAFD in the crude
diester composition 510. The DAFD rich stream desirably contains
DAFD present in an amount of at least 5 wt. %, or at least 10 wt %,
or at least 20 wt %, or at least 30 wt %, or at least 40 wt %, or
at least 50 wt %, or at least 60 wt %, and in each case up to 70
wt. %, or up to 80 wt %, in each case based on the weight of the
DAFD rich composition.
[0082] The first liquid DAFD rich stream desirably contains no
solids. If present, the solids comprise DAFD and/or unreacted FDCA
or other by-products reacting with DAFD and/or FDCA. The solids
concentration in the DAFD composition may contain no more than 55
wt. %, or up to 45 wt. %, or up to 35 wt. %, or up to 28 wt. %, or
up to 15 wt. %, or up to 10 wt. %, or up to 5 wt. %, or up to 3 wt.
%, or up to 2 wt. %, and if present, an amount of greater than
zero, each based on the weight of the first liquid DAFD rich
composition 620.
[0083] The first liquid DAFD rich composition stream 620 also
contains any alcohol that did not separate in the flash zone 600,
some water, and a quantity of some or all of the by-products
mentioned above. The amount of alcohol in the first liquid DAFD
rich stream is greater than zero, or at least 1 wt. %, or at least
2 wt. %, or at least 3 wt. %, or at least 5 wt. %, or at least 10
wt. %, or at least 15 wt. %, and up to 60 wt. %, or up to 50 wt. %,
or up to 40 wt. %, based on the weight of the DAFD rich stream.
[0084] As shown in FIG. 1, the first liquid DAFD rich composition
stream 620 is fed to a product recovery zone 700 to separate at
least a portion of DAFD from the first liquid DAFD rich composition
in the product recovery zone using one or more physical separation
processes to produce: [0085] (i) a purified DAFD vapor composition
rich in the concentration of DAFD relative to the concentration of
DAFD in the first liquid DAFD rich composition; and [0086] (ii) a
liquid ACFC composition that is rich in the concentration of ACFC
relative to the concentration of ACFC in the first liquid DAFD rich
composition; and [0087] (iii) a vapor AFC composition comprising
AFC that is rich in the concentration of AFC relative to the
concentration of AFC in the first liquid DAFD rich composition; and
[0088] (iv) a second vapor alcohol composition, comprising alcohol,
that is rich in the concentration of alcohol, relative to the first
liquid DAFD rich composition.
[0089] The product recovery zone 700 may contain one or more
distillation columns to effect one or more separations.
[0090] As an example, the product recovery zone 700 may contain an
alcohol-water removal zone 710, as shown in FIG. 3, comprising a
physical separation unit to separate alcohol from the first liquid
DAFD rich composition, thereby producing a second alcohol
composition stream 712 discharged from the top of the column that
is rich in the concentration of alcohol relative to the
concentration of alcohol in the first liquid DAFD rich composition
stream 620, and a second liquid DAFD rich composition stream 711
comprising DAFD that is rich in the concentration of DAFD relative
to the concentration of DAFD in the first liquid DAFD rich
composition stream 620. Desirably the concentration of alcohol in
the second liquid DAFD rich composition is depleeted (or lower)
relative to the concentration of alcohol in the first liquid DAFD
rich composition. Also, desirably the concentration of DAFD in the
second alcohol composition stream 712 discharged from the top of
the column is depleted relative to the concentration of DAFD in the
second liquid DAFD rich composition stream 711.
[0091] An example of a suitable devices for carrying out the
separation of alcohol from the first liquid DAFD rich composition
stream 620 is any type of distillation column (tray or packed).
[0092] The second alcohol composition stream 712 can, if desired,
be fed directly to the alcohol recovery zone 800 as a vapor to
separate water from the second alcohol composition stream 712.
Alternatively, the second alcohol composition stream 712 can, if
desired, be condensed, with a portion of the condensed alcohol
composition fed back to the column as reflux and a portion of the
condensed alcohol composition fed to the alcohol recovery zone 800
as a liquid. Thus, stream 712 fed to the alcohol recovery zone 800
is either a liquid and/or a vapor. The alcohol recovery zone 800
separates alcohol from the second alcohol composition stream 712.
The alcohol recovery zone 800 can also be used to accept a feed of
the first vapor alcohol composition stream 610 to separate alcohol
from the first vapor alcohol composition stream 610, and the same
distillation column can be used to accept feeds 610 and 712.
Alternatively, a second distillation column can be used to accept
feed 610.
[0093] Throughout this description, it is to be understood that any
vapor stream generated in the process, such as in each distillation
apparatus, can be condensed, and the condensation can occur inside
the column, outside the column, such as after the vapor is
discharged from the rectification section of the distillation
apparatus, and it can be partially or fully condensed.
Alternatively, the vapor stream does not have to be condensed at
all. It is also to be understood that any values describing the
concentration of an ingredient in a vapor stream can be measured on
a liquid stream condensed from the vapor stream in question if the
condensables in the vapor stream are fully condensed.
[0094] Alcohol recovery zone 800 generates a purified alcohol
composition stream 802 that is suitable for use as a recycle stream
fed to the esterification zone 500 if desired, and a water rich
stream 801 that is enriched in the concentration of water relative
to the concentration of water in the purified alcohol composition
stream 802. The concentration of water in the water rich stream 801
is desirably at least 98 wt. %, or at least 99 wt. %, or at least
99.5 wt. %.
[0095] Examples of suitable devices to separate alcohol from water
in the alcohol recovery zone include a distillation column, with
trays, or packed or both.
[0096] The vaporous purified alcohol composition stream 802,
whether or not condensed to use as a recycle stream to the
esterification zone, contains less than 10 wt. % water, or less
than 5 wt. % water, or less than 1 wt. % water, or less than 0.5
wt. % water, and less than 0.001 wt. % DAFD, or less than 0.0001
wt. % DAFD, each based on the weight of the purified alcohol
composition stream 802. In one embodiment, the purified alcohol
recycle stream 802 comprises methanol at a purity of greater than
99.0 wt. % based on the weight of the purified alcohol composition
stream.
[0097] The second liquid DAFD rich composition stream 711
discharged from the alcohol water removal zone 710 contains DAFD at
a concentration of at least 80 wt. %, or at least 85 wt. %, or at
least 90 wt. %, or at least 92 wt. %, and up to 99 wt. %, or up to
98 wt. %, or up to 97 wt. %, or up to 96 wt. %, each based on the
weight of the second liquid DAFD rich composition stream 711. The
amount of alcohol in the second liquid DAFD rich composition stream
is desirably less than 1 wt. %, or less than 0.1 wt. %, or less
than 0.01 wt. %, or less than 0.001 wt. %. The amount of water in
the second liquid DAFD rich composition 711 is desirably less than
1wt. %, or less than 0.5 wt. %, or less than 0.2 wt. %. The
concentration of DAFD in the second liquid DAFD rich composition
711 can be higher than the concentration of DAFD in the first
liquid DAFD rich composition stream 620 by at least 10 wt %, or at
least 20 wt %, or at least 30 wt %, or at least 40 wt %. The
cumulative concentration of water and alcohol in the second liquid
DAFD rich composition 711 is depleted relative to the concentration
of water an alcohol in the first liquid DAFD rich composition 620
by a factor of at least 100.times., or at least 300.times., or at
least 500.times., or at least 700.times..
[0098] The second liquid DAFD rich composition stream 711 contains
not only DAFD, but also ACFC, AFC, and AFFC. As shown in FIG. 3,
the second liquid DAFD rich composition 711 is fed to an AFC/AFFC
removal zone 720 to separate at least a portion of AFC from the
liquid DAFD rich composition using a physical separation process to
produce an AFC rich vapor composition 722 rich in the concentration
of AFC relative to the concentration of AFC in the second liquid
DAFD rich composition 711, and a partially purified liquid DAFD
rich composition stream 721 comprising DAFD and ACFC that is rich
in the concentration of DAFD relative to the concentration of DAFD
in the second liquid DAFD rich composition 711. Since AFC rich
vapor composition 722 is rich in the concentration of AFC relative
to the concentration of AFC in the second liquid DAFD rich
composition 711, it is necessarily also rich in the concentration
of AFC relative to the concentration of AFC in the first liquid
DAFD rich composition stream 620. Since DAFD in the partially
purified liquid DAFD rich composition stream 721 is rich in the
concentration of DAFD relative to the concentration of DAFD in the
second liquid DAFD rich composition 711, it is necessarily also
rich in the concentration of DAFD relative to the concentration of
DAFD in the first liquid DAFD rich composition stream 620.
[0099] An example of a suitable physical separation method is to
distill the second liquid DAFD rich composition 711. Suitable
distillation pot temperatures range in zone 720 from 200.degree. C.
to less than the boiling point of DAFD under the operating
conditions. Suitable temperatures range from 210.degree. C. to
280.degree. C., or 220.degree. C. to 260.degree. C., or 230.degree.
C. to 250.degree. C. The second liquid DAFD rich composition is
desirably distilled at a vacuum to avoid degrading the DAFD product
in the second DAFD rich composition in the pot that might otherwise
occur at higher temperatures. The second DAFD rich composition can
be distilled at pressures ranging from 1 psia to atmospheric
pressure. The column desirably has 10 to 70 trays, 10 to 60 trays
to, 10 to 50 trays, where a tray can be a valve tray, sieve tray,
bubble cap tray, or an equivalent height of a packed bed. The
distillation operating temperature desirably is set create an AFC
vapor composition and desirably to take off AFC vapor as a
distillate, which can optionally be partially or fully condensed
and a portion returned to the column as reflux. In another
embodiment, the distillation conditions can be set to also take off
AFFC in addition to AFC as a vapor overhead such that the
concentration of AFFC in the AFC rich vapor composition 722 is
enriched in the concentration of AFFC relative to the concentration
of AFFC in the second liquid DAFD rich stream 711. In this
embodiment, since AFC rich vapor composition 722 is rich in the
concentration of AFFC relative to the concentration of AFFC in the
second liquid DAFD rich composition 711, it is necessarily also
rich in the concentration of AFFC relative to the concentration of
AFFC in the first liquid DAFD rich composition stream 620.
[0100] The reflux ratio to achieve desired purities will vary with
the number of trays and the mass of distillate produced.
[0101] The composition of the AFC rich vapor stream 722 contains
AFC. The AFC rich vapor stream composition comprises at least 5 wt.
% AFC, or at least 10 wt. % AFC, or at least 15 wt. % AFC, or at
least 20 wt. % AFC, or at least 25 wt. % AFC. The AFC rich vapor
stream composition optionally comprises at least 2 wt. % AFFC, or
at least 5 wt. % AFFC, or at least 10 wt. % AFFC, or at least 20
wt. % AFFC, or at least 30 wt. % AFFC, or at least 40 wt. % AFFC,
or at least 50 wt. % AFFC, or at least 60 wt. % AFFC. The
concentration of AFFC in the AFC rich vapor stream 722 can be
higher than the concentration of AFC, in some cases by a factor of
1.5.times., or 2.times., or 2.5.times.. The concentration of DAFD
in the AFC rich vapor composition 722 is depleted relative to the
concentration of DAFD in the second liquid DAFD rich composition
stream 711. The concentration of DAFD in the AFC rich vapor
composition 722 can be less than 10 wt. % DAFD, or less than 5 wt.
% DAFD, or less than 4 wt. % DAFD, or less than 3 wt. % DAFD, or
less than 2 wt. % DAFD, or less than 1 wt. % DAFD, each based on
the weight of the AFC rich vapor composition. The concentration of
AFC and AFFC in the AFC rich vapor composition stream 722 can be at
least 20 wt %, or at least 40 wt. %, or at least 60 wt. %, or at
least 80 wt. %, or at least 90 wt. %, or at least 95 wt. %, each
based on the weight of all ingredients in the AFC rich vapor
composition 722.
[0102] The concentration of AFC in the AFC rich vapor composition
stream 722 is desirably increased by a factor of at least 5.times.,
or at least 10.times., or at least 15.times. and up to 80.times.,
or up to 70.times., or up to 50.times., on a weight basis, relative
to the concentration of AFC in the second liquid DAFD rich
composition 711.
[0103] The composition of the partially purified liquid DAFD rich
stream 721 contains DAFD and ACFC. The concentration of each of
these ingredients based on the weight of the partially purified
liquid DAFD rich stream 721 is as follows: [0104] DAFD: at least 90
wt. %, or at least 92 wt. %, or at least 95 wt. %, or at least 97
wt. %, or at least 98 wt. %, and up to 99.9 wt. %, or up to 99.5
wt. %, or up to 99.0 wt. %, or up to 98.5 wt. %, or up to 98 wt. %;
and [0105] ACFC: at least 0.05 wt. %, or at least 0.1 wt. %, or at
least 0.5 wt. %, or at least 1.0 wt. %, or at least 1.25 wt. %, and
up to 10 wt. %, or up to 7 wt. %, or up to 5.0 wt. %, or up to 4
wt. %, or up to 3 wt. %; and [0106] a cumulative amount of AFFC,
AFC, water and alcohol of less than 2 wt. %, or no more than 1.5
wt. %, or no more than 1.0 wt. %, or no more than 0.5 wt. %, or no
more than 0.1 wt %; and desirably also [0107] AFC and AFFC in an
amount of no more than 0.1 wt. %, or no more than 0.05 wt. %, or no
more than 0.001 wt. %.
[0108] The concentration of DAFD in the partially purified liquid
DAFD rich composition 721 is higher than the concentration of DAFD
in the second liquid DAFD rich composition 711. The concentration
of AFC in the partially purified liquid DAFD rich stream 721 is
desirably depleted relative to the concentration of AFC in the
second liquid DAFD rich composition 711 by a factor of at least
10.times., or at least 100.times., or at least 250.times., or at
least 500.times., or at least 750.times., or at least
1000.times..
[0109] The temperature of the partially purified liquid DAFD rich
stream effluent 721 from the AFC/AFFC removal zone 720 is desirably
at least 220.degree. C., or at least 230.degree. C. and up to
270.degree. C., or up to 260.degree. C., or up to 250.degree.
C.
[0110] The partially purified liquid DAFD rich composition stream
721 is fed to an ACFC removal zone 730 to separate at least a
portion of the DAFD from the partially purified liquid DAFD rich
composition 721 using a physical separation process to produce a
purified DAFD vapor composition 732 that is rich in the
concentration of DAFD relative to the concentration of DAFD in the
partially purified liquid DAFD rich composition 721, and a liquid
ACFC bottoms stream 731 that is rich in the concentration of ACFC
relative to the concentration of ACFC in the partially purified
liquid DAFD rich composition 721, each by weight. Since the
purified DAFD vapor composition 732 is rich in the concentration of
DAFD relative to the concentration of DAFD in the partially
purified liquid DAFD rich composition stream 721, it is necessarily
also rich in the concentration of DAFD relative to the
concentration of DAFD in the first liquid DAFD rich composition
stream 620. Since the liquid ACFC bottoms stream 731 is rich in the
concentration of ACFC relative to the concentration of ACFC in the
partially purified liquid DAFD rich composition stream 721, it is
necessarily also rich in the concentration of ACFC relative to the
concentration of ACFC in the first liquid DAFD rich composition
stream 620.
[0111] An example of a suitable physical separation apparatus is a
distillation column. Suitable distillation pot temperatures range
in zone 730 range from 200.degree. C. to less than the boiling
point of ACFC under the operating conditions. Desirably the
temperature is set to at least the boiling point of the DAFD
compound under the operating conditions. Suitable pot temperatures
range from 210.degree. C. to 280.degree. C., or 220.degree. C. to
260.degree. C., or 230.degree. C. to 255.degree. C. The partially
purified liquid DAFD rich composition 721 is desirably distilled at
a vacuum to avoid degrading the DAFD product. The partially
purified liquid DAFD rich composition 721 can be distilled at
pressures ranging from 1 psia to atmospheric pressure. The column
desirably has 10 to 70 trays, 10 to 60 trays to, or 10 to 50 trays,
where a tray can be a valve tray, sieve tray, bubble cap tray, or
an equivalent height of a packed bed. The distillation operating
temperature desirably is set create a purified DAFD vapor
composition and desirably to take off DAFD vapor as a distillate,
which can optionally be partially or fully condensed and a portion
returned to the column as reflux. The reflux ratio will vary with
the number of trays and the mass of distillate produced.
[0112] The composition of the purified DAFD vapor stream 732
contains DAFD. The concentration of each these ingredients by
weight based on the weight of the purified DAFD vapor stream is as
follows: [0113] DAFD: at least 99.0 wt. %, or at least 99.2 wt. %,
or at least 99.5 wt. %, or at least 99.7 wt. %, or at least 99.8
wt. %, or at least 99.9 wt. %, and up to 99.999 wt. %, or up to
99.995 wt. %, or at least 99.99 wt. %; and [0114] ACFC, that if
present at all, is present in an amount of greater than zero and
not greater than 1000 ppm, or not greater than 100 ppm, or not
greater than 10 ppm, or not greater than 1 ppm; and desirably
[0115] AFFC, that if present at all, is present in an amount of
greater than zero and not greater than 1000 ppm, or not greater
than 100 ppm, or not greater than 50 ppm, or not greater than 20
ppm. [0116] Optionally, this composition also contains very low
amounts or no amount of: AFC, that if present at all, is present in
an amount of not greater than 10 ppm, or not greater than 1 ppm, or
not greater than 0.1 ppm; and alcohol, that if present at all, is
present in an amount not greater than 10 ppm, or not greater than 1
ppm, or not greater than 0.1 ppm, and [0117] FDCA, if present at
all, is present in an amount of not greater than 1000 ppm, or not
greater than 100 ppm, or not greater than 10 ppm, or not greater
than 1 ppm.
[0118] Desirably, if water is present, it is present in an amount
of not greater than 1000 ppm, or not greater than 100 ppm, or not
greater than 10 ppm.
[0119] The concentration of ACFC in the purified DAFD vapor stream
732 is depleted relative to the concentration of ACFC in the
partially purified DAFD rich composition stream 721 by a factor of
at least 10.times., or at least 50.times., or at least 100.times.,
or at least 200.times..
[0120] The composition of the ACFC liquid bottoms composition 731
contains ACFC and DAFD. The ACFC liquid bottoms composition
comprises ACFC in an amount of at least 20 wt. %, or at least 30
wt. %, or at least 40 wt. % based on the weight of the ACFC liquid
bottoms composition. The concentration of DAFD in the ACFC liquid
bottoms composition desirably contains DAFD in an amount of less
than 70 wt. %, or less than 50 wt. %, or less than 40 wt. %, or
less than 30 wt. %, based on the weight of the ACFC liquid bottoms
composition. The amount of ACFC by weight is desirably at least
1.5.times., or at least 2.0.times. greater than the amount of DAFD
in the ACFC liquid bottoms stream.
[0121] The concentration of ACFC in ACFC liquid bottoms composition
731 is desirably increased by a factor of at least 5.times., or at
least 10.times., or at least 30.times. relative to the
concentration of ACFC in the partially purified liquid DAFD rich
composition 721.
[0122] The purified DAFD vapor composition is desirably condensed
in a condenser to produce a purified liquid DAFD product
composition containing liquefied DAFD at a temperature below the
boiling point the DAFD compound and above its crystallization
temperature at 1 atmosphere. The concentration of DAFD in the
purified liquid DAFD product composition, based on the purified
liquid DAFD product composition, is [0123] DAFD: at least 99.0 wt.
%, or at least 99.2 wt. %, or at least 99.5 wt. %, or at least 99.7
wt. %, or at least 99.8 wt. %, or at least 99.9 wt. %, and up to
99.999 wt. %, or up to 99.995 wt. %, or at least 99.99 wt. %; and
[0124] ACFC, that if present at all, is in an amount of not greater
than 100 ppm, or not greater than 10 ppm, or not greater than 1
ppm; and desirably [0125] AFFC, that if present, is present in an
amount of not more than 1000 ppm, or not more than 100 ppm, or not
more than 50 ppm, or not more than 20 ppm, and [0126] optionally,
AFC, that if present at all, is present in an amount of not greater
than 10 ppm, or not greater than 1 ppm, or not greater than 0.1
ppm; and [0127] optionally, alcohol, that if present at all, is
present in an amount not greater than 10 ppm, or not greater than 1
ppm, or not greater than 0.1 ppm; and desirably FDCA, if present at
all, is present in an amount of not greater than 1000 ppm, or not
greater than 100 ppm, or not greater than 10 ppm, or not greater
than 1 ppm.
[0128] Desirably, if water is present in the purified liquid DAFD
product composition, it is present in an amount of not greater than
1000 ppm, or not greater than 100 ppm, or not greater than 10 ppm,
or not greater than 5 ppm, or not greater than 1 ppm. The solids
concentration in the purified liquid DAFD product composition is
desirably 0, but if solids are present, they are present in an
amount of less than 0.1 wt %, or not more than 0.01 wt. %, or not
more than 0.001 wt. %.
[0129] If desired, the purified liquid DAFD product composition can
be hot. The hot purified liquid DAFD product composition can be
routed to a molten product storage tank, to train tanker car or
tanker truck capable of containing and transferring hot liquid
material, and/or directly to a polyester process through a pipeline
wherein DAFD is mixed with a polyester raw material comprising a
diol such as ethylene glycol and reacted with said diol to form
polymer comprising polyester.
[0130] Alternatively, the purified DAFD vapor composition can be
condensed and crystallized to form DAFD solid particles comprising
99.9 wt. % DAFD on a solids basis as a slurry, or instead of a
slurry, can be dried to form a dry DAFD solids stream, that in each
case has a purity of at least the same purity levels as in the
purified DAFD vapor rich stream 732. The conversion of the purified
liquid DAFD composition into a dry solid stream can be accomplished
by any other methods known in the art including a chilled belt
flaker, spray drying, and the like. Thus, there is also provided a
solids DAFD composition comprising solid particles of DAFD, wherein
said solids comprise: [0131] (i) at least 99.9 wt. % DAFD, or at
least 99.95 wt. % DAFD, or at least 99.99 wt. % DAFD; [0132] (ii)
not more than 1000 ppm, or not more than 100 ppm, or not more than
10 ppm ACFC 5-(alkoxycarbonyl)furan-2-carboxylic acid, [0133] (iii)
alkyl-5-formylfuran-2-carboxylate (AFFC) that if present, is
present in an amount of not more than 1000 ppm, or not more than
100 ppm, or not more than 10 ppm, and optionally [0134] (iv) not
more than 100 ppm, or not more than 100 ppm, or not more than 10
ppm, alkyl furan-2-carboxylate, and wherein the composition
contains not more than 1 wt. % water, or not more than 0.5 wt. %
water, or not more than 0.1 wt % water, or not more than 0.01 wt. %
water. Desirably, the composition contains less than 1000 ppm furan
dicarboxylic acid (FDCA), or less than 500 ppm FDCA, or less than
250 ppm FDCA, or less than 100 ppm FDCA, or less than 50 ppm FDCA,
or less than 20 ppm FDCA, or less than 10 ppm FDCA, or less than 5
ppm FDCA, or less than 3 ppm FDCA.
[0135] The process of the invention is described in further detail
in this example obtained by modeling using an ASPEN program:
[0136] For a given plant embodiment, a crude diester stream 510 is
provided which comprises 199,628 kg methanol/day; 11,346 kg
water/day; 508 kg MFC/day; 1,490 kg MFFC/day; 50,614 kg DMFD/day;
954 kg MCFC/day; and 479 kg FDCA impurities/day. The crude diester
stream 510 is at a temperature of 230.degree. C. and under a
pressure of 2,000 psia. The crude diester stream is fed to a flash
evaporation zone 600 where the pressure of the stream is reduced to
40 psia and by flash evaporation is split into two streams: an
vapor alcohol stream 610 that comprises 164,502 kg methanol/day;
7,959 kg water/day; 87 kg MFC/day; 5 kg MFFC/day; and 134 kg
DMFD/day; and a first liquid DAFD rich composition stream 620 which
comprises 35,126 kg methanol/day; 3,387 kg water/day; 421 kg
MFC/day; 1,485 kg MFFC/day; 50,480 kg DMFD/day; 954 kg MCFC/day;
and 479 kg FDCA impurities/day.
[0137] The first liquid DAFD rich composition stream 620 is fed to
a distillation column in the alcohol water removal zone 710 having
38 trays and set to a top pressure of 12 psia. The liquid bottoms
temperature is 225.degree. C. Methanol and water are removed as a
second alcohol rich distillate stream 712 comprising 35,126 kg
methanol/day; 3,338 kg water/day; and 18 kg MFC/day. The
distillation column underflow liquid stream, the second liquid DAFD
rich composition 711, comprises 49 kg water/day; 403 kg MFC/day;
1,485 kg MFFC/day; 50,480 kg DMFD/day; 954 kg MCFC/day; and 479 kg
FDCA impurities/day.
[0138] The vapor alcohol stream 610 and second alcohol rich stream
712 are fed to a distillation column in the alcohol recovery zone
800 for alcohol recovery and water purge. The distillation column
has 48 trays, is set at a top pressure of 8 psia, and has a liquid
bottoms temperature of 95.degree. C. The alcohol recycle distillate
stream 802 comprises 199,627 kg methanol/day; and 1,122 kg
water/day. The underflow water rich purge stream 801 comprises
10,174 kg water/day; 105 kg MFC/day; 5 kg MFFC/day; and 134 kg
DMFD/day.
[0139] The second liquid DAFD rich stream 711 is fed to a
distillation column in the AFC/AFFC removal zone 720. The
distillation column has 48 trays, is set at a top pressure of 3
psia, and has a liquid bottoms temperature of 242.degree. C. The
column distillate stream, the AFC rich vapor composition 722,
comprises 49 kg water/day; 403 kg MFC/day; 1,484 kg MFFC/day; 73 kg
DMFD/day; and 9 kg FDCA impurities/day as a process purge of
impurities. The column underflow stream, the partially purified
liquid DAFD rich composition 721, comprises 1 kg MFFC/day; 50,480
kg DMFD/day; 954 kg MCFC/day; and 470 kg FDCA impurities/day.
[0140] The partially purified liquid DAFD rich composition stream
721 is fed to a distillation column in ACFC removal zone 730. The
distillation column has 23 trays, is set at a top pressure of 1
psia, and has a liquid bottoms temperature of 248.degree. C. The
column distillate stream, the DAFD rich vapor 732, is the plant
DMFD product stream and comprises 1 kg MFFC/day; 50,000 kg
DMFD/day; 3 kg MCFC/day; and 5 kg FDCA impurities/day. The column
underflow stream, ACFC liquid bottoms stream 731, comprises 408 kg
DMFD/day; 951 kg MCFC/day; and 465 kg FDCA impurities/day.
[0141] The invention also includes a process for the manufacture of
FDCA, which is one of the raw materials fed to the esterification
zone 500. The process for the manufacture of FDCA will now be
described in more detail.
[0142] The process comprises feeding an oxidizable composition to
an oxidation zone, where the oxidizable composition contains a
compound having a furan moiety. The furan moiety can be represented
by the structure:
##STR00002##
[0143] The compounds having a furan moiety are such that, upon
oxidation, form carboxylic acid functional groups on the compound.
Examples of compounds having furnan moieties include
5-(hydroxymethyl)furfural (5-HMF), and derivatives of 5-HMF. Such
derivatives include esters of 5-HMF, such as those represented by
the formula 5-R(CO)OCH.sub.2-furfural where R=alkyl, cycloalkyl and
aryl groups having from 1 to 8 carbon atoms, or 1-4 carbon atoms or
1-2 carbon atoms; ethers of 5-HMF represented by the formula
5-R'OCH.sub.2-furfural, where R'=alkyl, cycloalkyl and aryl having
from 1 to 8 carbon atoms, or 1-4 carbon atoms or 1-2 carbon atoms);
5-alkyl furfurals represented by the formula 5-R''-furfural, where
R''=alkyl, cycloalkyl and aryl having from 1 to 8 carbon atoms, or
1-4 carbon atoms or 1-2 carbon atoms). Thus the oxidizable
composition can contain mixtures of 5-HMF and 5-HMF esters; 5-HMF
and 5-HMF ethers; 5-HMF and 5-alkyl furfurals, or mixtures of 5-HMF
and its esters, ethers, and alkyl derivatives.
[0144] The oxidizable composition, in addition to
5-(hydroxymethyl)furfural (5-HMF) or an of its derivatives, may
also contain 5-(acetoxymethyl)furfural (5-AMF) and
5-(ethoxymethyl)furfural (5-EMF).
[0145] Specific examples of 5-HMF derivatives include those having
the following structures:
##STR00003##
[0146] One embodiment is illustrated in FIG. 1. An oxidizable
composition is fed to a primary oxidation zone 100 and reacted in
the presence of a solvent, a catalyst system, and a gas comprising
oxygen, to generate a crude dicarboxylic acid stream 110 comprising
furan-2,5-dicarboxylic acid (FDCA).
[0147] For example, the oxidizable composition containing 5-HMF, or
its derivatives, or combinations thereof, are oxidized with
elemental O.sub.2 in a multi-step reaction to form FDCA with
5-formyl furan-2-carboxylic acid (FFCA) as a key intermediate,
represented by the following sequence:
##STR00004##
[0148] If desired, the oxygen gas stream 10 comprising oxygen, a
solvent stream 30, and the oxidizable stream 20 can be fed to the
primary oxidation zone 100 as separate streams. Or, an oxygen
stream 10 comprising oxygen as one stream and an oxidizable stream
20 comprising solvent, catalyst, and oxidizable compounds as a
second stream can be fed to the primary oxidation zone 100.
Accordingly, the solvent, oxygen gas comprising oxygen, catalyst
system, and oxidizable compounds can be fed to the primary
oxidization zone 100 as separate and individual streams or combined
in any combination prior to entering the primary oxidization zone
100 wherein these feed streams may enter at a single location or in
multiple locations into the primary oxidizer zone 100.
[0149] The catalyst can be a homogenous catalyst soluble in the
solvent or a heterogeneous catalyst. The catalyst composition is
desirably soluble in the solvent under reaction conditions, or it
is soluble in the reactants fed to the oxidation zone. Preferably,
the catalyst composition is soluble in the solvent at 40.degree. C.
and 1 atm, and is soluble in the solvent under the reaction
conditions.
[0150] Suitable catalysts components comprise at least one selected
from, but are not limited to, cobalt, bromine and manganese
compounds. Preferably a homogeneous catalyst system is selected.
The preferred catalyst system comprises cobalt, manganese and
bromine.
[0151] The cobalt atoms may be provided in ionic form as inorganic
cobalt salts, such as cobalt bromide, cobalt nitrate, or cobalt
chloride, or organic cobalt compounds such as cobalt salts of
aliphatic or aromatic acids having 2-22 carbon atoms, including
cobalt acetate, cobalt octanoate, cobalt benzoate, cobalt
acetylacetonate, and cobalt naphthalate. The oxidation state of
cobalt when added as a compound to the reaction mixture is not
limited, and includes both the +2 and +3 oxidation states.
[0152] The manganese atoms may be provided as one or more inorganic
manganese salts, such as manganese borates, manganese halides,
manganese nitrates, or organometallic manganese compounds such as
the manganese salts of lower aliphatic carboxylic acids, including
manganese acetate, and manganese salts of beta-diketonates,
including manganese acetylacetonate.
[0153] The bromine component may be added as elemental bromine, in
combined form, or as an anion. Suitable sources of bromine include
hydrobromic acid, sodium bromide, ammonium bromide, potassium
bromide, and tetrabromoethane. Hydrobromic acid, or sodium bromide
may be preferred bromine sources.
[0154] The amount of bromine atoms desirably ranges from at least
300 ppm, or at least 2000 ppm, or at least 2500 ppm, or at least
3000 ppm, or at least 3500 ppm, or at least 3750, ppm and up to
4500 ppm, or up to 4000 ppm, based on the weight of the liquid in
the reaction medium of the primary oxidation zone. Bromine present
in the an amount of 2500 ppm to 4000 ppm, or 3000 ppm to 4000 ppm
are especially desirable to promote high yield.
[0155] The amount of cobalt atoms can range from at least 500 ppm,
or at least 1500 ppm, or at least 2000 ppm, or at least 2500 ppm,
or at least 3000 ppm, and up to 6000 ppm, or up to 5500 ppm, or up
to 5000 ppm, based on the weight of the liquid in the reaction
medium of the primary oxidation zone. Cobalt present in an amount
of 2000 to 6000 ppm, or 2000 to 5000 ppm are especially desirable
to promote high yield.
[0156] The amount of manganese atoms can range from 2 ppm, or at
least 10 ppm, or at least 30 ppm, or at least 50 ppm, or at least
70 ppm, or at least 100 ppm, and in each case up to 600 ppm, or up
to 500 ppm or up to 400 ppm, or up to 350 ppm, or up to 300 ppm, or
up to 250 ppm, based on the weight of the liquid in the reaction
medium of the primary oxidation zone. Manganese present in an
amount ranging from 30 ppm to 400 ppm, or 70 ppm to 350 ppm, or 100
ppm to 350 ppm is especially desirable to promote high yield.
[0157] The weight ratio of cobalt atoms to manganese atoms in the
reaction mixture can be from 1:1 to 400:1, or 10:1 to about 400:1.
A catalyst system with improved Co:Mn ratio can lead to high yield
of FDCA. To increase the yield of FDCA, when the oxidizable
composition fed to the oxidation reactor comprises 5-HMF, then the
cobalt to manganese weight ratio is at least 10:1, or at least
15:1, or at least 20:1, or at least 25:1, or at least 30:1, or at
least 40:1 or at least 50:1, or at least 60:1, and in each case up
to 400:1. However, in the case where the oxidizable composition
comprises esters of 5-HMF, ethers of 5-HMF, or 5-alkyl furfurals,
or mixtures of any of these compounds together or with 5-HMF, the
cobalt to manganese weight ratio can be lowered while still
obtaining high yield of FDCA, such as a weight ratio of Co:Mn of at
least 1:1, or at least 2:1, or at least 5:1, or at least 9:1, or at
least 10:1, or at least 15:1, or at least 20:1, or at least 25:1,
or at least 30:1, or at least 40:1, or at least 50:1, or at least
60:1 and in each case up to 400:1.
[0158] The weight ratio of cobalt atoms to bromine atoms is
desirably at least 0.7:1, or at least 0.8:1, or at least 0.9:1,or
at least 1:1,or at least 1.05:1, or at least 1.2:1,or at least
1.5:1,or at least 1.8:1,or at least 2:1,or at least 2.2:1,or at
least 2.4:1,or at least 2.6:1,or at least 2.8:1,and in each case up
to 3.5, or up to 3.0, or up to 2.8.
[0159] The weight ratio of bromine atoms to manganese atoms is from
about 2:1 to 500:1.
[0160] Desirably, the weight ratio of cobalt to manganese is from
10:1 to 400:1, and the weight ratio of cobalt to bromine atoms
ranges from 0.7:1 to 3.5:1. Such a catalyst system with improved
Co:Mn and Co:Br ratio can lead to high yield of FDCA (minimum of
90%), decrease in the formation of impurities (measured by b*)
causing color in the downstream polymerization process while
keeping the amount of CO and CO.sub.2 (carbon burn) in the off-gas
at a minimum.
[0161] Desirably, the amount of bromine present is at least 1000
ppm and up to 3500 ppm, and the weight ratio of bromine to
manganese is from 2:1 to 500:1. This combination has the advantage
of high yield and low carbon burn.
[0162] Desirably, the amount of bromine present is at least 1000
ppm and up to 3000 ppm, and the amount of cobalt present is at
least 1000 ppm and up to 3000 ppm, and the weight ratio of cobalt
to manganese is from 10:1 to 100:1. This combination has the
advantage of high yield and low carbon burn.
[0163] Suitable solvents include aliphatic solvents. In an
embodiment of the invention, the solvents are aliphatic carboxylic
acids which include, but are not limited to, C.sub.2 to C.sub.6
monocarboxylic acids, e.g., acetic acid, propionic acid, n-butyric
acid, isobutyric acid, n-valeric acid, trimethylacetic acid,
caprioic acid, and mixtures thereof.
[0164] The most common solvent used for the oxidation is an aqueous
acetic acid solution, typically having a concentration of 80 to 99
wt. %. In especially preferred embodiments, the solvent comprises a
mixture of water and acetic acid which has a water content of 0% to
about 15% by weight. Additionally, a portion of the solvent feed to
the primary oxidation reactor may be obtained from a recycle stream
obtained by displacing about 80 to 90% of the mother liquor taken
from the crude reaction mixture stream discharged from the primary
oxidation reactor with fresh, wet acetic acid containing about 0%
to 15% water.
[0165] The oxidizing gas stream comprises oxygen. Examples include,
but are not limited to, air and purified oxygen. The amount of
oxygen in the primary oxidation zone ranges from about 5 mole % to
45 mole %, 5 mole % to 60 mole %, or 5 mole % to 80 mole %.
[0166] The temperature of the reaction mixture in the primary
oxidation zone can vary from about 100.degree. C. to about
220.degree. C. The temperature of the reaction mixture in the
primary oxidation zone is at least 100.degree. C., or at least
105.degree. C., or at least 110.degree. C., or at least 115.degree.
C., or at least 120.degree. C., or at least 125.degree. C., or at
least 130.degree. C., or at least 135.degree. C., or at least
140.degree. C., or at least 145.degree. C., or at least 150.degree.
C., or at least 155.degree. C., or at least 160.degree. C., and can
be as high as 220.degree. C., or up to 210.degree. C., or up to
200.degree. C., or up to 195.degree. C., or up to 190.degree. C.,
or up to 180.degree. C., or up to 175.degree. C., or up to
170.degree. C., or up to 165.degree. C., or up to 160.degree. C.,
or up to 155.degree. C., or up to 150.degree. C., or up to
145.degree. C., or up to 140.degree. C., or up to 135.degree. C.,
or up to 130.degree. C. In other embodiments, the temperate ranges
from 105.degree. C. to 180.degree. C., or from 105.degree. C. to
175.degree. C., or from 105.degree. C. to 160.degree. C., or from
105.degree. C. to 165.degree. C., or from 105.degree. C. to
160.degree. C., or from 105.degree. C. to 155.degree. C., or from
105.degree. C. to 150.degree. C., or from 110.degree. C. to
180.degree. C., or from 110.degree. C. to 175.degree. C., or from
110.degree. C. to 170.degree. C., or from 110.degree. C. to
165.degree. C., or from 110.degree. C. to 160.degree. C., or from
110.degree. C. to 155.degree. C., or from 110.degree. C. to
150.degree. C., or from 110.degree. C. to 145.degree. C., or from
115.degree. C. to 180.degree. C., or from 115.degree. C. to
175.degree. C., or from 115.degree. C. to 170.degree. C., or from
115.degree. C. to 167.degree. C., or from 115.degree. C. to
160.degree. C., or from 115.degree. C. to 155.degree. C., or from
110.degree. C. to 150.degree. C., or from 115.degree. C. to
145.degree. C., or from 120.degree. C. to 180.degree. C., or from
120.degree. C. to 175.degree. C., or from 120.degree. C. to
170.degree. C., or from 120.degree. C. to 165.degree. C., or from
120.degree. C. to 160.degree. C., or from 120.degree. C. to
155.degree. C., or from 120.degree. C. to 150.degree. C., or from
120.degree. C. to 145.degree. C., or from 125.degree. C. to
180.degree. C., or from 125.degree. C. to 175.degree. C., or from
125.degree. C. to 170.degree. C., or from 125.degree. C. to
165.degree. C., or from 125.degree. C. to 160.degree. C., or from
125.degree. C. to 155.degree. C., or from 125.degree. C. to
150.degree. C., or from 125.degree. C. to 145.degree. C., or from
130.degree. C. to 180.degree. C., or from 130.degree. C. to
175.degree. C., or from 130.degree. C. to 170.degree. C., or from
130.degree. C. to 165.degree. C., or from 130.degree. C. to
160.degree. C., or from 130.degree. C. to 155.degree. C., or from
130.degree. C. to 150.degree. C., or from 130.degree. C. to
145.degree. C., or from 135.degree. C. to 180.degree. C., or from
135.degree. C. to 175.degree. C., or from 135.degree. C. to
170.degree. C., or from 135.degree. C. to 170.degree. C., or from
135.degree. C. to 165.degree. C., or from 135.degree. C. to
160.degree. C., or from 135.degree. C. to 155.degree. C., or from
135.degree. C. to 150.degree. C., or from 135.degree. C. to
145.degree. C., or from 140.degree. C. to 180.degree. C., or from
140.degree. C. to 175.degree. C., or from 140.degree. C. to
170.degree. C., or from 140.degree. C. to 170.degree. C., or from
140.degree. C. to 165.degree. C., or from 140.degree. C. to
160.degree. C., or from 140.degree. C. to 155.degree. C., or from
140.degree. C. to 150.degree. C., or from 140.degree. C. to
145.degree. C., or from 145.degree. C. to 180.degree. C., or from
145.degree. C. to 175.degree. C., or from 145.degree. C. to
170.degree. C., or from 145.degree. C. to 170.degree. C., or from
145.degree. C. to 165.degree. C., or from 145.degree. C. to
160.degree. C., or from 145.degree. C. to 155.degree. C., or from
145.degree. C. to 150.degree. C., or from 150.degree. C. to
180.degree. C., or from 150.degree. C. to 175.degree. C., or from
150.degree. C. to 170.degree. C., or from 150.degree. C. to
165.degree. C., or from 150.degree. C. to 160.degree. C., or from
150.degree. C. to 155.degree. C., or from 155.degree. C. to
180.degree. C., or from 155.degree. C. to 175.degree. C., or from
155.degree. C. to 170.degree. C., or from 155.degree. C. to
165.degree. C., or from 155.degree. C. to 160.degree. C., or from
160.degree. C. to 180.degree. C., or from 160.degree. C. to
175.degree. C., or from 160.degree. C. to 170.degree. C., or from
160.degree. C. to 165.degree. C., or from 165.degree. C. to
180.degree. C., or from 165.degree. C. to 175.degree. C., or from
165.degree. C. to 170.degree. C., or from 165.degree. C. to
180.degree. C., or from 165.degree. C. to 175.degree. C., or from
165.degree. C. to 170.degree. C., or from 170.degree. C. to
180.degree. C., or from 170.degree. C. to 175.degree. C., or from
175.degree. C. to 180.degree. C.
[0167] To minimize carbon burn, it is desired that the temperature
of the reaction mixture is not greater than 165.degree. C., or not
greater than 160.degree. C. In the process of the invention, the
contents of the oxidizer off gas comprise COx, wherein x is 1 or 2,
and the amount of COx in the oxidizer off gas is less than 0.05
moles of COx per mole of the total oxidizable feed to the reaction
medium, or no more than 4 moles of COx per mole of the total
oxidizable feed to the reaction medium, or no more than 6 moles of
COx per mole of the total oxidizable feed to the reaction medium.
The carbon burn as determined by the COx generation rate can be
calculated as follows: (moles of CO+moles of CO2)/moles of
oxidizable feed. The low carbon burn generation rate in the process
of the invention is achievable by the combination of low reaction
temperature, and the molar weight ratios of the catalyst components
as described above.
[0168] The oxidation reaction can be conducted under a pressure
ranging from 40 to 300 psia. A bubble column is desirably operated
under a pressure ranging from 40 psia to 150 psia. In a stirred
tank vessel, the pressure is desirably set to 100 psia to 300
psia.
[0169] Oxidizer off gas stream 120 containing COx (CO and
CO.sub.2), water, nitrogen, and vaporized solvent, is routed to the
oxidizer off gas treatment zone 1000 to generate an inert gas
stream 810, liquid stream 820 comprising water, and a recovered
oxidation solvent stream 830 comprising condensed solvent. In one
embodiment, oxidizer off gas stream 120 can be fed to directly, or
indirectly after separating condensables such as solvent from
non-condensables such as COx and nitrogen in a separation column
(e.g. distillation column with 10-200 trays), to an energy recovery
device such as a turbo-expander to drive an electric generator.
Alternatively or in addition, the oxidizer off gas stream can be
fed to a steam generator before or after the separation column to
generate steam, and if desired, may then be fed to a turbo-expander
and pre-heated prior to entry in the expander if necessary to
ensure that the off gas does not condense in the
turbo-expander.
[0170] In another embodiment, at least a portion of the oxidation
solvent stream 830 recovered from the oxidizer off-gas stream is
routed to a filter and then to a wash solvent stream 320 to become
a portion of the wash solvent stream 320 for the purpose of washing
the solids present in the solid-liquid separation zone. In another
embodiment, the inert gas stream 810 can be vented to the
atmosphere. In yet another embodiment, at least a portion of the
inert gas stream 810 can be used as an inert gas in the process for
inerting vessels and or used for convey gas for solids in the
process.
[0171] The oxidation can be conducted in a continuous stirred tank
reactor or in a bubble column reactor.
[0172] The FDCA formed by the oxidation reaction desirably
precipitates out of the reaction mixture. The reaction mixture
comprises the oxidizable composition, solvent, and catalyst if a
homogeneous catalyst is used, otherwise it comprises the oxidizable
composition and solvent.
[0173] The product of the oxidation reaction is a crude
dicarboxylic acid stream 110 comprising FDCA as a solid, FDCA
dissolved in the solvent, solvent, and by-products and intermediate
products, and homogeneous catalyst system if used. Examples of
by-products include levulinic acid, succinic acid, and acetoxy
acetic acid. Examples of intermediate products include 5-formyl
furan-2-carboxylic acid (FFCA) and 2,5-diformylfuran.
[0174] The percent solids in the crude dicarboxylic acid stream
ranges is at least 10 wt %, or at least 15 wt. %, or at least 20
wt. %, or at least 25 wt. %, or at least 28 wt. %, or at least 30
wt. %, or at least 32 wt. %, or at least 35 wt. %, or at least 37
wt. %, or at least 40 wt. %. While there is no upper limit, as a
practice the amount will not exceed 60 wt. %, or no greater than 55
wt. %, or no greater than 50 wt. %, or no greater than 45 wt. %.,
or not greater than 43 wt. % ,or not greater than 40 wt %, or not
greater than 39 wt %. Of the solids in the crude dicarboxylic acid
stream, it is desirable that at least 80 wt. %, or at least 85 wt.
%, or at least 90 wt. %, or at least 95 wt. % of the solids in each
case is FDCA.
[0175] The stated amount of each of the following intermediates,
product, and impurities are based on the weight of the solids in
the crude carboxylic acid composition produced in the primary
oxidation reactor in the oxidation zone 100.
[0176] The amount of the intermediate FFCA present in the crude
dicarboxylic acid stream is not particularly limited. Desirably,
the amount is less than 4 wt. %, or less than 3.5 wt. %, or less
than 3.0 wt. %, or less than 2.5 wt. %, or up to 2.0 wt. %, or up
to 1.5 wt. %, or up to 1.0 wt. %, or up to 0.8 wt. %, based on the
weight of the solids present in the crude dicarboxylic acid
stream.
[0177] Impurities, if present in the crude dicarboxylic acid
composition, include such compounds as 2,5-diformylfuran, levulinic
acid, succinic acid, and acetoxy acetic acid. These compounds can
be present, if at all, in an amount of 0 wt % to about 0.2 wt % 2,5
difrmylfuran, levulinic acid in an amount ranging from 0 wt % to
0.5 wt %, succinic acid in an amount ranging from 0 wt % to 0.5 wt
% and acetoxy acetic acid in an amount ranging from 0 wt % to 0.5
wt %, and a cumulative amount of these impurities in an amount
ranging from 0 wt. % to 1 wt. %, or from 0.01 wt % to 0.8 wt. %, or
from 0.05 wt % to 0.6 wt. %, each based on the weight of the solids
present in the crude dicarboxylic acid stream.
[0178] In another embodiment of the invention the crude
dicarboxylic acid composition 110 comprises FDCA, FFCA and
5-(ethoxycarbonyl)furan-2-carboxylic acid ("EFCA"). The EFCA in the
crude dicarboxylic acid composition 110 can be present in an amount
of at least 0.05 wt %, or at least 0.1 wt %, or at least 0.5 wt %
and in each case up to about 4 wt %, or up to about 3.5 wt %, or up
to 3 wt. %, or up to 2.5 wt %, or up to 2 wt. %, based on the
weight of the solids present in the crude dicarboxylic acid
stream.
[0179] The yield of FDCA, on a solids basis and measured after the
drying zone step, is at least 60%, or at least 65%, or at least
70%, or at least 72%, or at least 74%, or at least 76%, or at least
78%, or at least 80%, or at least 81%, or at least 82%, or at least
83%, or at least 84%, or at least 85%, or at least 86%, or at least
87%, or at least 88%, or at least 89%, or at least 90%., or at
least 91%, or at least 92%, or at least 94%, or at least 95%, and
up to 99%, or up to 98%, or up to 97%, or up to 96%, or up to 95%,
or up to 94%, or up to 93%, or up to 92%, or up to 91%, or up to
90%, or up to 89%. For example, the yield can range from 70% up to
99%, or 74% up to 98%, or 78% up to 98%, or 80% up to 98%, or 84%
up to 98%,or 86% up to 98%,or 88% up to 98%,or 90% up to 98%,or 91%
up to 98%,or 92% up to 98%, or 94% up to 98%, or 95% up to 99%.
[0180] Yield is defined as mass of FDCA obtained divided by the
theoretical amount of FDCA that should be produced based on the
amount of raw material use. For example, if one mole or 126.11
grams of 5-HMF are oxidized, it would theoretically generate one
mole or 156.01 grams of FDCA. If for example, the actual amount of
FDCA formed is only 150 grams, the yield for this reaction is
calculated to be =(150/156.01) times 100, which equals a yield of
96%. The same calculation applies for oxidation reaction conducted
using 5-HMF derivatives or mixed feeds.
[0181] The maximum b* of the dried solids, or wet cake, is not
particularly limited. However, a b* of not more than 20, or no more
than 19, or no more than 18,or no more than 17,or no more than
16,or no more than 15,or no more than 10,or no more than 8,or no
more than 6, or no more than 5, or no more than 4, or no more than
3, is desirable without having to subject the crude carboxylic acid
composition to hydrogenation. However, if lowered b* is important
for a particular application, the crude carboxylic acid composition
can be subjected to hydrogenation.
[0182] The b* is one of the three-color attributes measured on a
spectroscopic reflectance-based instrument. The color can be
measured by any device known in the art. A Hunter Ultrascan XE
instrument is typically the measuring device. Positive readings
signify the degree of yellow (or absorbance of blue), while
negative readings signify the degree of blue (or absorbance of
yellow).
[0183] In the next step, which is an optional step, the crude
dicarboxylic acid stream 110 can fed to a cooling zone 200 to
generate a cooled crude dicarboxylic acid slurry stream 210 and a
1.sup.st solvent vapor stream 220 comprising solvent vapor. The
cooling of crude carboxylic slurry stream 110 can be accomplished
by any means known in the art. Typically, the cooling zone 200 is a
flash tank. All or a portion of the crude dicarboxylic acid stream
110 can be fed to the cooling zone.
[0184] All or a portion of the crude dicarboxylic acid stream 110
can be fed to solid-liquid separation zone 300 without first being
fed to a cooling zone 200. Thus , none or only a portion can be
cooled in cooling zone 200. The temperature of stream 210 exiting
the cooling zone can range from 35.degree. C. to 160.degree. C.,
55.degree. C. to 120.degree. C., and preferably from 75.degree. C.
to 95.degree. C.
[0185] The crude dicarboxylic acid stream 110, or 210 if routed
through a cooling zone, is fed to a solid-liquid separation zone
300 to generate a crude carboxylic acid wet cake stream 310
comprising FDCA. The functions of isolating, washing and dewatering
the crude carboxlic acid stream may be accomplished in a single
solid-liquid separation device or multiple solid-liquid separation
devices. The solid-liquid separation zone 300 comprises at least
one solid-liquid separation device capable of separating solids and
liquids, washing solids with a wash solvent stream 320, and
reducing the % moisture in the washed solids to less than 30 weight
%. Desirably, the solid-liquid separation device is capable of
reducing the % moisture down to less than 20 weight %, or less than
15 weight %, and preferably 10 weight % or less. Equipment suitable
for the solid liquid separation zone can typically be comprised of,
but not limited to, the following types of devices: centrifuges of
all types including but not limited to decanter and disc stack
centrifuges, solid bowl centrifuges, cyclone, rotary drum filter,
belt filter, pressure leaf filter, candle filter, and the like. The
preferred solid liquid separation device for the solid liquid
separation zone is a continuous pressure drum filter, or more
specifically a continuous rotary pressure drum filter. The
solid-liquid separator may be operated in continuous or batch mode,
although it will be appreciated that for commercial processes, the
continuous mode is preferred.
[0186] The temperature of crude carboxylic acid slurry stream, if
cooled as stream 210, fed to the solid-liquid separation zone 300
can range from 35.degree. C. to 160.degree. C., 55.degree. C. to
120.degree. C., and is preferably from 75.degree. C. to 95.degree.
C.
[0187] The wash stream 320 comprises a liquid suitable for
displacing and washing mother liquor from the solids. For example,
the wash solvent comprises acetic acid, or acetic acid and water,
an alcohol, or water, in each case up to an amount of 100%. The
temperature of the wash solvent can range from 20.degree. C. to
180.degree. C., or 40.degree. C. and 150.degree. C., or 50.degree.
C. to 130.degree. C. The amount of wash solvent used is defined as
the wash ratio and equals the mass of wash divided by the mass of
solids on a batch or continuous basis. The wash ratio can range
from about 0.3 to about 5, about 0.4 to about 4, and preferably
from about 0.5 to 3.
[0188] There can be multiple washes with the same wash solvent or
with different wash solvents. For example a first wash comprising
acetic acid may be followed by a second wash comprising the alcohol
utilized in the downstream esterification reaction zone.
[0189] After solids are washed in the solid liquid separation zone
300, they are dewatered. Dewatering can take place in the solid
liquid separation zone or it can be a separate device from the
solid-liquid separation device. Dewatering involves reducing the
mass of moisture present with the solids to less than 30% by
weight, less than 25% by weight, less than 20% by weight, and most
preferably less than 15% by weight so as to generate a crude
carboxylic acid wet cake stream 310 comprising FDCA. Dewatering can
be accomplished in a filter by passing a gas stream through the
solids to displace free liquid after the solids have been washed
with a wash solvent. Alternatively, dewatering can be achieved by
centrifugal forces in a perforated bowl or solid bowl
centrifuge.
[0190] One or more washes may be implemented in solid-liquid
separation zone 300. One or more of the washes, preferably at least
the final wash, in solid-liquid separation zone 300 comprises a
hydroxyl functional compound as defined further below, such as an
alcohol (e.g. methanol). By this method, a wet cake stream 310 is
produced comprising the hydroxyl functional compound such as
methanol in liquid form. The amount of the hydroxyl functional
compound in liquid form in the wet cake can be at least 50 wt %, or
at least 75 weight %, or at least 85% weight %, or at least 95
weight % hydroxyl functional compound such as methanol based on the
weight of the liquids in the wet cake stream. The advantage of
adopting this technique of washing with a hydroxyl functional
compound is that a portion or all of the wet cake can be fed to the
esterification zone 500 without undergoing, or by-pass, a step of
feeding the wet cake to a vessel for drying the wet cake in a
drying zone 400 after the solid-liquid separation zone.
[0191] In one embodiment, 100% of wet cake stream 310 is fed to
esterification reaction zone 500 without undergoing or subjecting
the wet cake to a vessel for drying the wet cake from the solid
liquid separation zone 300.
[0192] Stream 330 generated in solid-liquid separation zone 300 is
a liquid mother liquor stream comprising oxidation solvent,
catalyst, and impurities. If desired, a portion of mother liquor
stream 330 can be fed to a purge zone 900 and a portion can be fed
back to the primary oxidation zone 100, wherein a portion is at
least 5 weight % based on the weight of the liquid. Wash liquor
stream 340 is also generated in the solid-liquid separation zone
300 and comprises a portion of the mother liquor present in stream
210 and wash solvent wherein the weight ratio of mother liquor mass
to wash solvent mass in the wash liquor stream is less than 3 and
preferably less than 2. From 5% to 95%, from 30% to 90%, and most
preferably from 40 to 80% of mother liquor present in the crude
carboxylic acid stream fed to the solid-liquid separation zone 200
is isolated in solid-liquid separation zone 300 to generate mother
liquor stream 330 resulting in dissolved matter comprising
impurities present in the displaced mother liquor not going forward
in the process. The mother liquor stream 330 contains dissolved
impurities removed from the crude dicarboxylic acid.
[0193] Sufficient hydroxyl functional compound such as an alcohol
(e.g. methanol) is fed to the solid liquid separation zone 300 that
becomes mixed with solids present resulting in a low impurity
slurry stream 310 being pumpable with weight % solids ranging from
1% to 50%, 10% to 40%, and preferably the weight % solids in stream
310 will range from 25% to 38%.
[0194] In one embodiment, from 5% to 100% by weight of the
displaced mother liquor stream 330 is routed to a purge zone 900
wherein a portion of the impurities present in stream 330 are
isolated and exit the process as purge stream 920, wherein a
portion is 5% by weight or greater. Recovered solvent stream 910
comprises solvent and catalyst isolated from stream 330 and is
recycled to the process. The recovered solvent stream 910 can be
recycled to the primary oxidation zone 100 and contains greater
than 30% of the catalyst that entered the purge zone 900 in stream
330. The stream 910 recycled to the primary oxidation zone 100 may
contain greater than 50 weight %, or greater than 70 weight %, or
greater than 90 weight % of the catalyst that enters the purge zone
900 in stream 330 on a continuous or batch basis.
[0195] Optionally, a portion up to 100% of the crude carboxylic
acid composition may be routed directly to a secondary oxidation
zone (not shown) before being subjected to a solid liquid
separation zone 300.
[0196] Generally, oxidation in a secondary oxidation zone is at a
higher temperature than the oxidation in the primary oxidation zone
100 to enhance the impurity removal. In one embodiment, the
secondary oxidation zone is operated at about 30.degree. C.,
20.degree. C., and preferably 10.degree. C. higher temperature than
the oxidation temperature in the primary oxidation zone 100 to
enhance the impurity removal. The secondary oxidation zone can be
heated directly with solvent vapor, or steam via stream or
indirectly by any means known in the art.
[0197] Additional purification of the crude carboxylic acid stream
can be accomplished in the secondary oxidation zone by a mechanism
involving recrystallization or crystal growth and oxidation of
impurities and intermediates including FFCA. One of the functions
of the secondary oxidation zone is to convert FFCA to FDCA. FFCA is
considered monofunctional relative to a polyester condensation
reaction because it contains only one carboxylic acid. FFCA is
present in the crude carboxylic acid composition stream. FFCA is
generated in the primary oxidation zone 100 because the reaction of
5-HMF to FFCA can be about eight times faster than the reaction of
FFCA to the desired di-functional product FDCA. Additional air or
molecular oxygen may be fed to the secondary oxidation zone in an
amount necessary to oxidize a substantial portion of the partially
oxidized products such as FFCA to the corresponding carboxylic acid
FDCA. Generally, at least 70% by weight, or at least 80 wt %, or at
least 90 wt % of the FFCA present in the crude carboxylic acid
composition exiting the primary oxidation zone can be converted to
FDCA in the secondary oxidation zone. Significant concentrations of
monofunctional molecules like FFCA in the dried, purified FDCA
product are particularly detrimental to polymerization processes as
they may act as chain terminators during the polyester condensation
reaction.
[0198] If a secondary oxidation zone is employed, the secondary
oxidation slurry can be crystallized to form a crystallized slurry
stream. Vapor from the crystallization zone can be condensed in at
least one condenser and returned to the crystallization zone or
recycled, or it can be withdrawn or sent to an energy recovery
device. The crystallizer off-gas can be removed and routed to a
recovery system where the solvent is removed, and crystallizer off
gas containing VOC's may be treated, for example, by incineration
in a catalytic oxidation unit. The crystallizer can be operated by
cooling the secondary oxidation slurry to a temperature between
about 40.degree. C. to about 175.degree. C. to form a crystallized
slurry stream.
[0199] The crystallzed slurry stream can then be subjected to a
cooling zone 200 if desired and the process continued as described
above.
[0200] Instead of using a wet cake, one may produce a dried solid.
The wet cake produced in the solid liquid separation zone 300 can
be dried in a drying zone 400 to generate a dry purified carboxylic
acid solid 410 and a vapor stream 420. The vapor stream 420
typically comprises the wash solvent vapor used in the solid liquid
separation zone, and may additionally contain the solvent used in
the primary oxidation zone. The drying zone 400 comprises at least
one dryer and can be accomplished by any means known in the art
that is capable of evaporating at least 10% of the volatiles
remaining in the purified wet cake stream to produce the dried,
purified carboxylic acid solids. For example, indirect contact
dryers include, but are not limited to, a rotary steam tube dryer,
a Single Shaft Porcupine dryer, and a Bepex Solidaire dryer. Direct
contact dryers include, but are not limited to, a fluid bed dryer
and drying in a convey line.
[0201] The dried, purified carboxylic acid solids comprising
purified FDCA can be a carboxylic acid composition with less than
8% moisture, preferably less than 5% moisture, and more preferably
less than 1% moisture, and even more preferably less than 0.5%, and
yet more preferably less than 0.1%.
[0202] A vacuum system can be utilized to draw vapor stream 420
from the drying zone 400. If a vacuum system is used in this
fashion, the pressure at the dryer outlet can range from about 760
mmHg to about 400 mmHg, from about 760 mmHg to about 600 mmHg, from
about 760 mmHg to about 700 mmHg, from about 760 mmHg to about 720
mmHg, and from about 760 mmHg to about 740 mmHg wherein pressure is
measured in mmHg above absolute vacuum.
[0203] The dried, purified carboxylic acid solids, or the solids in
the wet cake, desirably have a b* less than about 9.0, or less than
about 6.0, or less than about 5.0, or less than about 4.0. or less
than about 3.
[0204] It should be appreciated that the process zones previously
described can be utilized in any other logical order to produce the
dried, purified carboxylic acid. It should also be appreciated that
when the process zones are reordered that the process conditions
may change. It is also understood that all percent values are
weight percents.
[0205] One function of drying zone 400 is to remove by evaporation
oxidation solvent comprising a mono-carboxylic acid with 2 to 6
carbons that can be present in the crude carboxylic acid wet cake
stream 310. The % moisture in crude carboxylic acid wet cake stream
310 typically ranges from 4.0% by weight to 30% by weight depending
on the operation conditions of the solid-liquid separation zone
300. If for example, the liquid portion of stream 310 is about 90%
acetic acid, the amount of acetic acid present in stream 310 can
range from about 3.6 weight % to 27 weight %. It is desirable to
remove acetic acid prior to esterification zone 500 because acetic
acid will react with the alcohol present in the zone 500 to create
unwanted by products. For example, if methanol is fed to
esterification zone 500 for the purpose of reacting with FDCA, it
will also react with acetic acid present to form methyl acetate and
therefore consume methanol and generate an unwanted by-product. It
is desirable to minimize the acetic acid content of the crude
carboxylic acid stream comprising FDCA that is fed to
esterification zone 500 to less than 3.6 weight %, preferably less
than 1 weight %, and more preferably less than 0.5 weight %, and
most preferably less than 0.1 weight %. One method for achieving
this is to dry a crude carboxylic acid wet cake stream 310
comprising acetic acid prior to routing the crude carboxylic to
esterification zone 500. Another method for minimizing the
oxidation solvent comprising mono-carboxylic acid with carbons
ranging from 2 to 5 in the crude carboxylic acid stream 410 routed
to esterification zone 500 to an acceptable level without utilizing
a dryer zone 400 is to conduct non-monocarboxylic acid wash or
washes in solid-liquid separation zone 300 to wash the oxidation
solvent from the solids with a wash comprising any wash solvent
compatible with the esterification zone 500 chemistry to generate a
crude carboxylic acid wet cake stream 310 suitable for routing
directly to esterification zone 500 without being dried in drying
zone 400. Acceptable wash solvents comprise solvents that do not
make undesirable by products in esterification zone 500. For
example, water is an acceptable wash solvent to displace acetic
acid from solids in solid-liquid separation zone 300. Another
acceptable wash solvent is an alcohol that will be used as a
reactant in the esterification zone 500. There can be multiple and
separate washes in the solid liquid separation zone 300. A wash
feed can comprise water up to 100 weight %. A wash feed can
comprise an alcohol up to 100 weight %. A wash feed can comprise
methanol up to 100%. A wash feed can comprise the same alcohol
utilized in the esterification zone 500 for reaction with FDCA to
form the di-ester product. In one embodiment, a wet cake dewatering
step can be used after the wet cake is formed in the solid liquid
separation zone 300 and before any non-acetic acid wash is
employed. This dewatering step ill minimize the liquid content of
the wet cake prior to washing with a non-acetic acid wash solvent
such as water and or methanol as described above, thus minimizing
the cost to separate any mixtures of acetic acid and non-acetic
acid wash solvents that are generated in solid-liquid separation
zone 300.
[0206] The solid dicarboxylic acid composition 410, which can be
either dried carboxylic acid solids or wet cake, comprising FDCA,
and the alcohol composition stream 520 are fed to the
esterification reaction zone 500. The solid dicarboxylic acid
composition 410 can be shipped via truck, ship, or rail as solids.
However, an advantage of the invention is that the process for the
oxidation of the oxidizable material containing the furan group can
be integrated with the process for the manufacture of the crude
diester composition.
[0207] An integrated process includes co-locating the two
manufacturing facilities, one for oxidation and the other for
esterification, within 10 miles, or within 5 miles, or within 2
miles, or within 1 mile, or within 1/2 mile of each other. An
integrated process also includes having the two manufacturing
facilities in solid or fluid communication with each other. If a
solid dicarboxylic acid composition is produced, the solids can be
conveyed by any suitable means, such as air or belt, to the
esterification facility. If a wet cake dicarboxylic acid
composition is produced, the wet cake can be moved by belt or
pumped as a liquid slurry to the facility for esterification.
* * * * *